WARSAW -- A Polish military aircraft bearing the coffin of President Lech Kaczynski has arrived in Warsaw, a day after he was killed in a plane crash in western Russia.

Acting President Bronislaw Komorowski, Prime Minister Donald Tusk, and other officials met the coffin today at the military airport after its flight from Smolensk in western Russia where the crash occurred in thick fog on April 10.

Poland held two minutes of silence at noon to mourn the killed president and the nearly 100 others who perished in the plane crash.

Kaczynski and scores of other Polish government, military, and church officials were due to attend a ceremony marking the 70th anniversary of the massacre of thousands of Polish military officers by Soviet forces at the Katyn forest in western Russia.

A week of mourning has been called in Poland.

Komorowski said he would set the date for a new presidential election within two weeks.

Russia has declared April 12 a day of mourning and Prime Minister Vladimir Putin said he would oversee the investigation into the crash.

Russian officials have suggested that heavy fog or an error by the Polish crew may have played a role in the accident.